If it’s parts holding it up not much they can do I guess. That being said if it’s going to take a stupid time then the insurance will either have to give up and write it off then repair it on their time and sell it to recover their loss meanwhile you’d be told to choose a new car.
Or they’re going to have to find the parts some other way whether it’s a used good part from a wrecked car or whatever, depends on the part.
First port of call is speak to directline find out their position then go to Motability.
Fully agree with you about the hire cars I’ve got a 3 year old 3008 that stinks like an ashtray had to put two air fresheners in it to deaden the cigarette smell which upsets me hugely as my dad died from cancer a few years ago from passive smoking over 20 years in a closed office, and the smell just rubs salt in the wound. That and the windows are scratched up badly, paintwork is awful and it’s covered in dents lol.
Hope you make some progress on it but definitely make those calls